Plastic shotgun shell

ABSTRACT

AN ALL PLASTIC SHOTGUN SHELL COMPRISED OF A TUBULAR PLASTIC CASING HAVING AN INTEGRAL BASE WALL WITH AN APERTURE THEREIN THROUGH WHICH A PRIMER EXTENDS, A PLASTIC OVER-SHOT WAD CLOSING THE END OF SAID TUBULAR CASING OPPOSITE SAID BASE WALL, A ONE-PIECE PLASTIC SHOT CUP AND OVER-POWDER WAD UNIT WITHIN THE TUBULAR CASING, AND A PLASTIC BASE WAD SEATED WITHIN SAID CASING AGAINST SAID BASE WALL. THERE IS A NON-BINDING FIT BETWEEN THE PRIMER AND THE APERTURE IN THE CASING BASE WALL, THE PRIMER BEING FIRMLY GRIPPED AND   HELD IN PLACE BY MEANS OF A FORCE FIT BETWEEN THE PRIMER AND AN AXIAL POCKET FORMED WITHIN THE YIELDABLE BASE WAD INTO WHICH THE PRIMER EXTENDS.

Oct. 26, 1971 R R ETAL 3,614,929

PLASTIC SHOTGUN SHELL Filed April 21, 1969 INV/i/V'I'UR. 40 64 5'9 58 622 GEORGE L. Alt/e752 BY GLE/V 4. m/rrasrzoar W *M Arron/Er:

United States Patent Olfice 3,614,929 Patented Oct. 26, 1971 3,614,929PLASTIC SHOTGUN SHELL George L. Herter and Glen L. Mittelsteadt, Waseca,lVIinn., assignors to Herters, Inc., Waseca, Minn. Filed Apr. 21, 1969,Ser. No. 817,860 Int. Cl. F42b 7/06, 7/08 US. Cl. 10243 P 6 ClaimsABSTRACT OF THE DISCLOSURE An all plastic shotgun shell comprised of atubular plastic casing having an integral base wall with an aperturetherein through which a primer extends, a plastic over-shot wad closingthe end of said tubular casing opposite said base wall, a one-pieceplastic shot cup and over-powder wad unit within the tubular casing, anda plastic base wad seated within said casing against said base wall.There is a non-binding fit between the primer and the aperture in thecasing base wall, the primer being firmly gripped and held in place bymeans of a force fit between the primer and an axial pocket formedwithin the yieldable base wad into which the primer extends.

BRIEF SUMMARY OF THE INVENTION The shotgun shell of this invention isparticularly characterized by an all plastic structure which lendsitself to relatively simple and inexpensive manufacturing, which isparticularly adapted for multiple use and reloading of the severalcomponents, and which is specially constructed and arranged so as toeliminate the problem of distorting or rupturing the shell casing at itsbase end resulting from the pressures generated by an exploding chargedetonated within the shell casing.

These basic objectives are realized by a unique design of the base orhead end of the plastic shotshell which provides for the retention of aprimer in the base wall of the shell in such a way as to prevent theexertion of undue outward force on the casing base wall by the primer asit is detonated. The great radial force transmitted by the primer to thebase end of the shell casing upon detonation of the primer andpropellant charge has been a major cause of cracking and rupturing ofthe base end of plastic shotshells. This problem is attributable, inpart at least, to the base structure of prior art plastic shotshellswherein'the primer is tightly fitted into a pocket or cavity in the basewall of the shell casing. In accordance with our new plas tic shotshelldesign, the plastic casing of the shotshell is provided with an integralbase wall having an aperture therein through which a primer extends in arelatively loose, free fit therewith. The primer is held in place by aplastic base wad having an axially extending, central cavity withinwhich the primer is tightly fitted so as to be retained in the desiredposition. The shock and pressure transmitted by the detonating primer isabsorbed almost entirely by the plastic base wad, which is formed fromyieldable and resilient plastic material, thereby preventing thetransmission of potentionally damaging forces and shock waves to thelower end of the shell casing and its base wall.

As a particularly advantageous feature of our improved plasticshotshell, we utilize a plurality of axially spaced rings projectinginwardly from the interior surface of the aforesaid central cavity inthe base wad to grip the primer and firmly hold it in place. As the basewad deforms under the pressure exerted by the exploding propellantcharge within the shell casing, the rings on the base wad cavity areforced inwardly in tight, sealing engagement with the primer so as toprevent the leakage of combustion gases downwardly around the primer.Peripheral sealing teeth on the external surface of the base wad tightlyengage the interior wall surface of the shell casing so as to precludethe leakage of gases between the base wad and the plastic casing.

A further beneficial feature of our improved plastic shotshell residesin the use of an annular groove in the top surface of the base wad, thedownward fiow of combustion gases into said groove on detonation of thepropellent charge causing the opposed side walls of said groove to beforced apart, thereby assisting in moving said sealing rings and teethinto tight engagement with the primer and the plastic casingrespectively.

In addition to the aforesaid plastic casing and base wad, the allplastic shell structure further includes a plastic shot cup andover-powder wad of unitary construction and a top closure wad which ispreferably formed from the same relatively soft, plastic material as thebase wad.

These and other objects and advantages of our invention will becomereadily apparent as the following description is read in conjunctionwith the accompanying drawings wherein like reference numerals have beenused to designate like elements throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section viewshowing the all plastic shotshell of this invention;

FIG. 2 is a top view of the shell of FIG. 1 showing the top, closurewad;

FIG. 3 is a fragmentary, vertical section view showing the lower end ofthe shell of FIG. 1 and the shape of the base wad upon detonation;

FIG. 4 is a top plan view of the base wad of this invention;

FIG. 5 is an elevation view, partially in section, of the base Wad; and

FIG. 6 is a bottom plan view of the base wad of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,we have shown in FIG. 1 a preferred embodiment of our improved, allplastic shotgun shell utilizing a tubular casing 1 having an integralbase wall 2 at one end thereof. Casing 1 is preferably molded fromrelatively hard plastic material such as polycarbonate, base wall 2being formed integrally with casing 1 during the molding operation so asto thereby provide a one-piece casing and base wall unit. By moldingbase wall 2 integrally with casing 1, we have simplified themanufacturing procedure by eliminating the need for gluing, welding orotherwise bonding a closure base to the head or base end of tubularcasing 1. A peripheral flange 4 on base wall 2 serves as a contactelement for an ejection mechanism in a shotgun.

Disposed within casing 1 is a shot cup 6 which contains a plurality ofshot pellets 8, and which preferably comprises one portion of a unitaryshot cup and overpowder wad element designated generally by referencenumeral 10. Unitary element 10 is molded from pliable and yieldableplastic such as polyethylene, and includes a transversely extendingoverpowder wad 12 at its bottom end. Depending from over-powder wad 12is a powder enclosing and sealing skirt 14 comprised of inner and outerannular walls 15 and 16. A plurality of spacing and sealing discs orrings 18 extend transversely outwardly from center post 20 of unitaryover-powder wad and shot cup and bear against the inside surface oftubular casing 1 at their outer ends. Central post 20 of element 10 isaxially compressible to thereby provide a shock absorbing and cushioningeffect to assist in absorbing the pressures generated by the detonationof a propellent charge 22 contained under over-powder wad 12.

The open, upper end of tubular casing 1 is closed by means of a topclosure wad 24 which is also molded from soft, yieldable polyethyleneplastic. Closure wad 24 is comprised of a relatively thin, transverselyextending central section 26 and a peripheral rim 28. The necessarystrength is imparted to central section 26 by means of a plurality ofradially extending ribs 30 which extend along both the upper and lowersurfaces of wall section 26. The radial orientation of strengtheningribs 30 is shown in FIG. 2. Peripheral ring section 28 is beveled aroundits outer periphery on both the upper and lower faces thereof, thebeveled surfaces being indicated at 32 and 33 in FIG. 1. The undersideof top closure wad 24 bears against the top end of shot cup 6 and shotpellets 8, and it is held in contact therewith by inwardly crimped upperend portion 34 of tubular casing 1 in the manner shown in FIGS. 1 and 2.Crimped end portion 34 of easing 1 is turned inwardly at a slight angleto conform to the angle of beveled surfaces 32 and 33 of closure wad 24.The provision of beveled surfaces 32 and 33 and strengthening ribs 30 onboth the upper and lower faces of closure wad 24 renders wad 24reversible so as to eliminate the need for orienting it with aparticular face directed upwardly during the assembly of the shotgunshell.

The remaining element of our all plastic shotgun shell is a functionallyimportant base wad designated by reference numeral 36. Base wad 36 isformed from soft, yieldable plastic preferably polyethylene, and is ofgenerally cylindrical configuration as is shown in FIGS. 4, 5 and 6. Thebottom surface 38 of base wad 36 is substantially flat and planar so asto seat flush against flat inner surface 40 of base wall 2 when base wad36 is inserted into the base or head end of tubular casing 1 in theposition shown in FIG. 1.

At its lower end, base wad 36 has a substantially conical outer wallsurface 42 which nests within and conforms to inner conical wall surface44 at the lower end of tubular casing 1. A plurality of longitudinallyspaced rings 44 are provided around the outer periphery of base wad 36at its upper end, rings 36 terminating at relatively sharp edges 45 tothereby define a plurality of spaced teeth in vertical cross-section asshown in FIGS. 1 and 5. Edge portions 45 of rings 44 engage the innerwall surface of tubular casing 1 and assist in holding base wad 36 inplace. The upper end of base wad 36 is dished inwardly and is defined byconcave top wall 46 which cooperates with over-powder Wad 12 to form thespace within which propellent charge 22 is contained. Relatively thinwall section 48 at the upper end of base wad 36 between top wall 46thereof and the outer peripheral surface of wad 36 is readilycompressible and deformable, thereby rendering base wad 36 particularlyeffective as a cushioning and shock absorbing device.

Extending axially of base wad 36 and disposed substantially centrallythereof is a tubular cavity or pocket 50 within which a primerisreceived and retained in a manner hereinafter described. The upper endof primer cavity 50 communicates with the powder containing space abovetop wall 46 of base wad 36 through a reduced diameter flash passage 52.The smaller diameter of flash passage 52 compared to the diameter oftubular cavity 5i) provides a shoulder 54 against which the upper end ofa primer abuts. The primer gripping and retaining function of cavity 50may be improved by providing a plurality of longitudinally spaced rings56 along the surface thereof. Rings 56 project radially inwardly fromthe wall surface of cavity 50 and are sized to tightly grip a primer 58shown in place in FIG. 1. Base wad 36 further includes an annular groove60 formed within upper wall 46 thereof between flash passage 52 and theperipheral surface of wad 36. Groove 60 serves a dual function as both ameans of reshaping base wad 36 as required after use and as a pressuretransmitting surface in a manner explained below.

Referring again to FIG. 1, it Will be seen that base wall 2 is providedwith an aperture 62 through which primer 58 extends. A slightly largerdiameter recess 64 in the bottom face of base wall 2 serves as a seatfor the rim 59 of primer 58. It is to be noted that base wall 2 has athickness somewhat greater than that of the vertically extending portionof tubular casing 1 to increase the strength of base 'wall 2 and improveits ability to satisfactorily withstand the shock and pressure generatedby the explosion of propellent charge 22. However, it is also to benoted that base wall 2 has a thickness substantially less that thelength of primer 58, whereby primer 58 is contained over the greaterportion of its length within tubular cavity 50 of base wad 36. Centralaperture 52 in base wall 2 is sized so that it has a diameter equal toor slightly greater than the maximum diameter permitted for primer 58within tolerance limitations. For example, if primer 58 has a maximumdiameter of .242 inch, then the minimum diameter of aperture 62 will be.242 inch. By virture of this structural arrangement, primer 58 may beinserted freely through aperture 62 into tubular cavity 50 in anon-binding, relatively loose fit with aperture 62. Primer 58 isactually firmly gripped and held in place by tubular cavity 50 of basewad 36. This is accomplished by sizing the diameter of cavity 50 so thatit is significantly less than the diameter of primer 58. Thus, afterpassing freely through aperture 62 in base wall 2, primer 58 must beforced upwardly into reduced diameter cavity 50. As primer 58 is forcedinto cavity 50 the yieldable and resilient plastic material of base wad36 which defines cavity 50 is compressed radially outwardly and thenflexes inwardly in tight, gripping engagement with the exterior surfaceof primer 58. The secure retention of primer 58 within cavity 50 isfurther insured by rings 56 which are of even smaller diameter thancavity 50 and thus bear against primer 5-8 very tightly. Because primer58 is firmly gripped and held in place by base wad 36 and is not intight, friction contact With aperture 62 of base wall 2, the outwardforces exerted *by primer 62 when it is struck by a firing hammer andexplodes are absorbed almost entirely by yieldable and resilient basewad 36. A very minimum amount of shock and pressure is transmitted tobase wall 2, with the result that cracking and deforming of plastic basewall 2 is effectively prevented.

Upon the detonation of primer 58 and the explosion of propellent charge22, base wad 36 will be deformed and compressed downwardly in the mannershown in FIG. 3. The relatively small thickness of wall section 48permits upper wall surface 46 of base Wad 36 to be compressed downwardlyand radially outwardly to the position shown in FIG. 3 in response tothe downward force exerted by the combustion gases within the spacebetween over-powder wad 12 and base wad 36. Teethlike sealing rings 44will be forced downwardly and pressed together to thereby provide acushioning and shock absorbing effect as top, concave Wall 46 of basewad 36 is urged downwardly. Due to its concave shape, wall 46 will alsoreceive and transmit force radially outwardly with he result thatpointed, peripheral edges 45 of sealing rings 44 will be forcedoutwardly into tight contact with the inside surface of tubularcasing 1. An effective seal will thus be provided along the lower,

inside surface of casing 1 to prevent expanding gases from flowingdownwardly between base wad 36 and casing 1 towards base wall 2. Thepressure of the combustion gases acting within annular slot 60 of basewad 36 will also cause the side walls of slot 60 to be forced apart inthe manner shown in FIG. 3. As the outside side wall 61 of slot 60 movesoutwardly it assists in moving peripheral teeth 44 into tight, sealingcontact with the inside surface of tubular casing 1. Inside wall 63 ofslot 60 will be forced inwardly, thereby assisting in pressing rings 56of cavity 50 into very tight, sealing engagement with primer 58. Thefirm contact of resilient, pliable polyethylene rings 56 against primer58 provides a very tight seal which prevents the leakage of combustiongases downwardly around the outside surface of primer 58. Thecompression and deformation of polyethylene base wad 36 in the mannerdescribed above provides very effectively for the cushioning andabsorption of the forces and shock waves generated by the explodingpropellent charge with the result that the lower end of relatively hardplastic casing 1, as well as base wall 2, are extremely well protectedagainst deformation or cracking upon detonation of the propellentcharge. Moreover, as noted above, since primer 58 is firmly grippedwithin yieldable base wad 36 and fits relatively loosely within aperture62 of base wall, 2, the outward forces transmitted from primer 58 whenit is detonated are substantially entirely absorbed by yieldable anddeformable base wad 36, thereby eliminating the cracking or deformationof base Wall 2 which frequently occurred on prior art plastic shotgunshells having the primer tightly held within an aperture in the plasticbase wall.

Polyethylene base wad 36, being resilient as well as yieldable anddeformable, will normally return to its original shape after theshotshell in which it is used has been fired. Thus, plastic casing 1 and"base wad 36 may be reloaded and reused a considerable number of times.If primer cavity 50 does expand radially upon detonation of the primer,annular slot 60 in upper wall 46 of base wad 36 may be utilized tocompress the walls of cavity 50 back inwardly to their originaldiameter. This is accomplished by inserting a sleeve or tubularextension on a reloading tool into slot 60 and exerting downward forceon base wad 36 as it is pressed into the lower end of tubular casing 1.The downward force exerted by the reloading tool on the bottom ofannular groove 60 will compress the lower end of base wad 36 and assistin forcing the side walls of cavity 50 inwardly to their originalposition.

Although we have shown and described our improved all plastic shotshellwith respect to preferred embodiments thereof, those skilled in the artwill readily appreciate that various changes could be made in theshotshell design Without loosing the benefits of the particular base wadstructure described herein. For example, base wad 36 could be held inplace by being wedged into the lower end of casing 1 rather than byusing peripheral teeth 44. Also, in lieu of contact rings or teeth 44, aplurality of dimples in the outer surface of base wad 36 could beutilized to hold base wad 36 in the plastic case. Also, although rings56 on the inside wall surface of primer cavity 50 assist in holdingprimer 58 in place, they are not essential. As long as the diameter ofprimer cavity 50 is sized properly so that it is substantially less thanthe diameter of primer 58, the yieldable plastic walls of cavity 50 willfirmly and tightly engage primer 50 and effectively hold it in placeafter it is forced into cavity 50.

We claim:

1. An all plastic shotshell comprising in combination:

a tubular casing constructed entirely of relatively hard,

polycarbonate plastic, said casing having a tubular case wall andterminating at one end in an integral base wall to provide a one piececasing and base wall unit, said base wall being substantially fiat andof uniform thickness, and having a central aperture sized to permit theinsertion of a primer therethrough in a free, non-binding fit therewith,the thickness of said base wall being substantially less than the lengthof the primer to be inserted therethrough and greater than the thicknessof said tubular case wall;

a relatively soft, yieldable plastic closure wad secured Within theopposite end of said tubular casing;

a one-piece plastic shot cup and over-powder wad unit disposed withinsaid tubular casing; and

a base wad of relatively soft, yieldable plastic material positionedwithin said casing in abutting contact with the inside surface of saidbase wall and defining with said over-powder wad a space for apropellent charge, said base wad having an elongated, central cavity inalignment with said aperture in said base wall and sized to engage aprimer inserted therein in firm, gripping contact therewith.

2. A shotshell as defined in claim 1 wherein:

said closure wad has a beveled surface extending circumferentiallyaround its outer periphery and is held in place by a short, inwardlycrimped portion of said opposite end of said tubular casing which bearsagainst said beveled surface of said closure wad in conformingengagement therewith.

3. A shotshell as defined in claim 1 and further including:

a primer received within said central cavity of said base wad andextending through said central aperture in said base wall, said aperturein said base wall being of equal or greater diameter than said primerinserted therethrough, and said central cavity in said base wad having adiameter slightly less than that of said primer received therein,whereby said primer extends through said base wall aperture in a free,non-binding fit therewith and is received in a force fit with saidcentral cavity of said yieldable, plastic base wad so as to be tightlyengaged and retained by the walls of said base wad cavity.

4. A shotshell as defined in claim 1 wherein:

a plurality of longitudinally spaced rings project inwardly from thewall surface of said base wad cavity, said rings being sized to tightlygrip said primer and thereby assist in holding it in place; and

said base wad includes an annular groove in the upper surface thereofbetween said central cavity and the outer periphery of said base wad,the downward flow of pressurized combustion gases into said groove upondetonation of said propellent charge causing the opposed side walls ofsaid groove to be forced apart, thereby forcing said rings on saidcentral cavity into tight, sealing engagement with a primer containedWithin said cavity.

5. A shotshell as defined in claim. 4 wherein:

said base wad further includes a plurality of longitudinally spaced,circumferentially extending sealing teeth on its peripheral surface,said teeth being in contact with the inside surface of said tubularcasing and being forced into sealing engagement therewith as said basewad deforms in response to the pressure generated by the detonation ofsaid propellent charge.

6. An empty, primed shotgun shell to be assembled with shot and powdercharges into a shotshell, comprising:

a tubular casing constructed entirely of relatively hard unyieldingplastic, said casing having a tubular case wall and a transverse basewall formed integrally with each other in a single, one piececonstruction, said base wall having substantially fiat inner and outersurfaces and a substantially uniform thickness across the entire widththereof, said base wall further having a central aperture therein toaccept a primer therein in a non-binding fit;

said aperture having a counterbore adjacent the outer surface of thebase wall to define a depressed ledge References Cited adjacent theouter surface; UNITED STATES PATENTS a primer projecting into andthrough said aperture in the base Wall in a non-binding relationship to3298313 1/1967 Comerford 1O242 c the periphery of the aperture, saidprimer having a 5 3,359,906 12/1967 Herter 1O295 peripheral bead seatedon said ledge; 3,517,617 1/1970 Han 10242 and a base wad of relativelysoft yieldable plastic ma- FOREIGN PATENTS terial positioned Within saidcasing in abutting con- 1,294,551 4/1962 France 102-43 tact with theinner periphery of the tubular case Wall, said base Wad further having asubstantially 10 flat bottom surface bearing against the inner sur-ROBERT STAHL Pnmary Examiner face of said base Wall over substantiallythe entire width thereof, and an elongated central cavity aligned withthe aperture in the base Wall and re- 10243 C, 95; 112-44 ceiving andtightly gripping the primer and retain- 1 ing the primer in a stationaryposition.

